The perfect Seal doesn’t existWhy seals, O-rings, mastics and joints let in water
(and how to improve them!)

The perfect seal does not exist. Water, hydrocarbon and other vapours seep through the actual materials seals are made from. Some materials are good at keeping liquid water out – but many of them are very poor when they come to vapours.

It was an humble O-ring that caused the space shuttle Challenger to explode.

So it’s important to know if you are using, or developing, the right seal, mastic or O-ring for your application. And it’s important to know if each batch performs to the same standard as all-too-often they don’t.

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Traditionally this has been a difficult, very time consuming (sometimes taking weeks for a single measurement) and expensive process, especially if you need to check material samples as well as finished products, which have previously required different techniques.

Versaperm Limited, a world leader in water vapour permeability measurement, has introduced a simple way to test all of this with a single, fast, piece of equipment.

The new Versaperm’s Vapour Transmission meter can cope with several samples, seals or enclosures at a time, often give a reading in as little as 30 minutes – conventional gravimetric testing takes days or even weeks to achieve the same thing and is significantly less accurate.

Seals and enclosures can be highly sensitive to changes in pressure, temperature and other conditions. Testing is the only way to ensure that a seal is fit-for-purpose and that Quality Control is being maintained.

The Versaperm Equipment is computer controlled and needs, at most, minimal training to give results that are accurate to a few parts per million (a few parts per billion for some materials). No re-calibration is needed and the equipment can be configured to detect not only water vapour,but also hydrocarbon vapours, Oxygen, CO2 and almost any other vapour.

As well as manufacturing the instruments, Versaperm offers a vapour permeability laboratory service for companies that only need to test samples on an irregular basis.